The United States is preparing for a "preventive war" with North Korea among many options to deal with its missile and nuclear threats, President Trump's top security adviser has said.

In an interview aired Saturday on MSNBC, National Security Adviser H.R. McMaster said the president has been clear he will not tolerate North Korea's threats to attack the U.S. with nuclear weapons.

A preventive war is initiated to prevent an enemy from carrying out an attack.

"What you're asking is are we preparing plans for a preventive war, right?" McMaster said. "If they have nuclear weapons that can threaten the United States. It's intolerable from the president's perspective. So of course, we have to provide all options to do that. And that includes a military option."

North Korea carried out two tests of intercontinental ballistic missiles last month, claiming the entire U.S. mainland is within its striking range.

Trump's willingness to go to war with North Korea was mentioned by Sen. Lindsey Graham (R-SC) earlier this week. He said the president told him there would be a war with North Korea if the regime continues to try to hit America with an ICBM.

Many experts doubt the North has mastered the technology to mount a nuclear weapon on a missile capable of reaching the U.S. But they also recognize the faster than expected pace of development of its nuclear and missile programs. (Yonhap)